How “brain covers” protect the brain

This journey begins with a visit to the brain covers. We can find three brain covers in-between the hard skull and the brain. We call them “meninges”. They act as cushions while protecting the brain from friction.

But, that is not their only job.

The outermost brain cover: Dura mater (“tough mother”)

The outermost cover is the thickest and the firmest of all three; hence the name: Dura mater meaning “tough mother”.

Figure 1 shows only the left half of the Dura mater. It is an old drawing. In reality, it contains two layers. The outer one attaches to the inner side of the skull. The inner one glistens. And, it is also transparent. Because of its transparency, we can see a network of blood vessels running inside.

view Brain: dissection showing the top of the brain, with the dura mater of the left hemisphere and the gyri of the right. Watercolour after(?) W.H. Lizars, ca. 1826.
Figure 1: Dura mater
Credit: Brain: dissection showing the top of the brain, with the dura mater of the left hemisphere and the gyri of the right. Watercolour after(?) W.H. Lizars, ca. 1826. Credit: Wellcome CollectionAttribution 4.0 International (CC BY 4.0)

Other two brain covers: Arachnoid mater and Pia mater

Now, we look at the two inner covers. Inside the Dura matter, the other two thinner coverings (Figures 2 and 3) spread all over the brain surface. These covers are also transparent. Unlike the outer covering, they wrap the brain surface throughout all grooves and bumps of the brain surface. The middle layer is full of fluid, called cerebrospinal fluid.

This image shows a cross-section through the brain. The different meningeal layers are labeled.
Figure 2: Dura mater and Pia mater;
source: openstax.org, RICE University
under the CC BY 4.0 license
figure1
Figure 3: Brain covers and blood-carrying vessels;
Source: BioMed Central, a part of Springer Nature Natividad et al. under the CC BY 4.0 license.

In-between the two layers harbour a fluid – named cerebrospinal fluid (in short CSF). Not only that, small branches of arteries traverse throughout the layers. They carry oxygen and food to the neuron forest and other structures.

Why should we know about this?

Why should we know this information? This is the reason; when a small branch of the artery bursts or is damaged blood leaks out and fills the space between the two covers. Depending on the volume, the leaked blood builds pressure on the pliable brain surface. As a result, it may exert pressure on neurons in that area. This undue pressure disrupts its job. Sometimes this pressure may even cause death. It has to be stopped.

An excellent video clip can be found from the University of Utah through this link: https://neurologicexam.med.utah.edu/adult/html/brain-dissections.html#10

Other journeys to the brain

Author: Ed Jerard

Research analyst and health promoter in Canada

Leave a Reply

Your email address will not be published. Required fields are marked *